The Ubuntu operating system must have an application firewall enabled.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-100911	UBTU-18-010520	SV-110015r1_rule		Medium

Description
Firewalls protect computers from network attacks by blocking or limiting access to open network ports. Application firewalls limit which applications are allowed to communicate over the network.

STIG	Date
Canonical Ubuntu 18.04 LTS Security Technical Implementation Guide	2020-05-29

Details

Check Text ( C-99777r1_chk )
Verify the Uncomplicated Firewall is enabled on the system by running the following command: # systemctl status ufw.service \| grep -i "active:" Active: active (exited) since Mon 2016-10-17 12:30:29 CDT; 1s ago If the above command returns the status as "inactive", this is a finding. If the Uncomplicated Firewall is not installed ask the System Administrator if another application firewall is installed. If no application firewall is installed this is a finding.

Check Text ( C-99777r1_chk )

Verify the Uncomplicated Firewall is enabled on the system by running the following command:

# systemctl status ufw.service | grep -i "active:"

Active: active (exited) since Mon 2016-10-17 12:30:29 CDT; 1s ago

If the above command returns the status as "inactive", this is a finding.

If the Uncomplicated Firewall is not installed ask the System Administrator if another application firewall is installed. If no application firewall is installed this is a finding.

Fix Text (F-106603r1_fix)
Enable the Uncomplicated Firewall by using the following command: # sudo systemctl enable ufw.service If the Uncomplicated Firewall is not currently running on the system, start it with the following command: # sudo systemctl start ufw.service